Drilling machine



Sept. 20, 1955 J. A. MxLLER DRILLING MACHINE NHSB IIA' :3.

Filed June `15, 1954 nited States Patent O DRILLING MACHINE .lohn A.Miller, Fremont, Ohio Application .inne 15, 1954, Serial No. 436,776

Claims. (Cl. Z55-4.4)

This invention relates to rock drilling devices such as are used inquarrying for drilling holes into which explosives are to be packed forblasting. Such holes may be from a few feet deep to as much as or morethan sixty feet deep.

lt is a general object of this invention to provide a drilling devicewhich will function electively at any depth.

More specifically it is an object of this invention to provide adrilling machine in which mass of reciprocating parts, rapidity ofreciprocation, length of stroke, resiliency and other characteristicsare so coordinated that rapidly repeated reactions substantiallycounterbalance gravity to keep the body of the machine spaced above therock being drilled at a substantially constant distance from which apiston repeatedly plunges a bit against the rock.

Ancillary objects are to provide a drilling machine of simple and sturdyconstruction which will continue to operate reliably under abusivehammering conditions and in atmospheres loaded with abrasive particles.

Other objects and advantages will be apparent upon perusal of thefollowing description illustrated by the accompanying drawings in which:

Fig. I is an elevational view of a drilling machine embodying theinstant invention, an outer casing and a cylinder and chest being shownin section and a part of a piston rod being broken out;

Fig. II is an enlarged sectional view of parts of the outer casing andthe cylinder and chest and parts contained therein;

Fig. III is a plan view of an upper cylinder head.

Fig. 1V is an elevational view of the upper cylinder head certaininterior details being shown in dash lines.

Fig. V is an elevational view of a lower cylinder head.

The mechanism of the drilling machine is mounted within a tubular shell8, which may be of any desired dimensions e. g., four to six inches indiameter and five to ten feet long.

Mounted within the lower end of the shell 8 and retained therein by apair of pins 9 and a threaded ring 1t) is a composite engine casingcomprising an upper tubular chest 11, an intermediate cylinder 12, and alower tubular section 13.

Screwed into the upper end of the tubular chest 11is a threaded plug 14having a threaded opening into which is screwed a pipe or nipple 15adapted to conduct an expansive fluid such as steam or compressed airinto the tubular chest 11. The expansive fluid may be supplied by a hosewhich extends to a source of supply outside of the hole being drilled.

Interposed between the tubular chest 11 of the composite engine casingand the intermediate cylinder 12 is an upper cylinder head 16 havingarcuate sides that t ing reduced threaded ends 20 and 21 upon whichinternally threaded ends of the intermediate cylinder 12 and the lowersection 13 are screwed.

From the tubular chest 11 expansive fluid such as steam or compressedair is conducted by a conduit 22 to the upper cylinder head 16 and tothe lower cylinder head 19.

Within the intermediate cylinder 12 reciprocates a piston 24. Fixed tothe piston 24 is a piston rod 25 which passes through a bearing plug 26tting within the lower end of the shell 8 and has a reduced threadedpart that is screwed into the lower end of the lower section 13. Thelower section thus serves as a holder which spaces the bearing plug 26far enough from the lower cylinder head 19 to insure against binding orjamming of the piston or piston rod.

The upper cylinder head 16 is provided with an inlet passage 27 leadingfrom the conduit 22 to the space in the cylinder 12 above the piston 24.Interposed in the inlet passage 27 is an inlet valve 28 which is openedby an inlet valve tappet during the final part of the upward stroke ofthe piston 24. The inlet valve tappet consists essentially of a tappetrod 29 which is slidable through the upper cylinder head 16 and which isprotected against peening by cushioning springs 30 interposed betweenthe tappet rod and its tips 31. Fixed to the tappet rod 29 is a block 32which is located within the passage 27 and is secured to the stern 33 ofthe inlet valve 28, the stem 33 also being slidably mounted in the uppercylinder head 16. Thus when the piston 24 strikes the lower tip 31 ofthe tappet rod 29 the tappet rod 29, the block 32 and the inlet valvestern 33 will be pushed up as a unit to open the inlet valve 28.

The upper cylinder head 16 is provided also with an exhaust passage 34leading from the space in the cylinder 12 above the piston 24 to anexhaust pipe 35. The exhaust passage 34 is closed and opened by anexhaust valve 36 whose stem 37 is slidably mounted in the upper cylinderhead 16 and is fixed to a block 38 that is located within the exhaustpassage 34. An exhaust valve tappet rod 39 is slidably mounted in thecylinder head 16 and is xed to the block 38. The exhaust valve tappetrod 39 is equipped with spring cushioned tips 31 identical with those onthe inlet valve tappet rod 29. When the piston 24 strikes the lower tipof the exhaust valve tappet rod 39 it will push the exhaust valve tappetrod 39, the block 38 and the valve stem 37 up as a unit thus closing theexhaust valve 36.

In Figs. II and IV the parts are shown in their relationship just as thepiston 24 reaches the lower tips 31 of the tappet rods 29 and 39 whilethe inlet valve 28 still is closed and the exhaust valve 36 still isopen. The

. linal upward movement of the piston through a fraction enter the upperend of the cylinder 12 as long as the within the shell 8 and havingreduced threaded ends 17 inlet valve remains open.

Fixed to the piston 24 and extending upwardly therefrom through iluidtight packing in the cylinder head 16 is an auxiliary rod 40 whichcarries a plate 41. When the piston 24 comes within a small fraction ofan inch of the end of its downward stroke the plate 41 will strike thespring cushioned upper tips of the tappet rods 29 and 39 and thus close`the inlet valve 28 and open the exhaust valve 36 so that the piston 24can be driven upwardly. Admission of expansive fluid into the space inthe cylinder 12 below .the piston 24 .and exhaust .0f eX- pansive uidfrom such space is accomplished by mechanism mounted in the lowercylinder head. This mechanism diters from that inthe upper cylinder headprincipally in that pairs of :small valves are employed in the lowercylinder head rather than .single large valves such as are yemployed inthe .upper cylinder head.

The lower cylinder head 19 .is provided with :an inlet passage 42leading from the conduit 22 .to .the space in the cylinder 12 beneaththe piston 24. interposed in the inlet passage 42 is a pair .of inletvalves .43 which are opened by a lower inlet valve tappet .during the-inal part of =the vdownward stroke .of the piston 24. The lower inletvalve tappet consists essentially .of a tappet rod 44 which is -slidablethrough the lower .cylinder head 19 and which is protected againstpeening by cushioning springs 30 interposed lbetween the tappet rod andits tips 31. Fixed to the tappet rod 44 is a block 45 which is loca-tedwithin Athe inlet passage 42 and .is secured to the stems 46 of theinlet valves 43, the stems 46 `also being slidably mounted in @the lower:cylinder head 19. Thus when the piston 24 strikes the upper tip 31 ofthe tappet rod 44.1the tappet rod 44, the 'block 45 and the inlet valvestems 46 are pushed down as a unit to open the inlet valves43.

The lower cylinder .head 19 is Vprovided also with an exhaust passage 47leading from the space in the cylinder 12 beneath the piston 24 to theexhaust pipe 35. The exhaust passage 47 is closed and opened by a pairof exhaust valves 48 whose stems 49 are slidably mounted in the lowercylinder head 19 and are fixed to a block 50 that is located within theexhaust passage 47. An exhaust valve tappet rod S1 is slidably mountedin the lower cylinder head 19 and is fixed to the block 50. The exhaustvalve tappet rod -is equipped with spring cushioned tips 31.

When the piston 24 strikes the upper tip of the lower exhaust valvetappet rod 51 -it pushes the tappet rod 51, the block 50 .and the valvestems 49 down as a unit thus closing Vthe exhaust valves 48.

Fixed to the piston -rod 25 -is an -annulus 52. When the piston 24 comesto within a fraction of an inch of its upward stroke the annnlus 52 willstrike the lower spring Acushioned tips of the tappet rods 44 and 51 andthus push -the vtappet rods up to close the inlet valves 43 and open the-exhaust valves 48, so that the piston 24 again jcan be drivendownwardly.

Accidental partial or full opening or closing of any of the valves ofthe lapparatus is prevented i-n each case by a pair of balls 53 whichare pressed by expansive springs 54 into a pair of sockets in the block-xed xto the tappet rod when the valve is closed and ywhich cam out yofthose sockets and snap into another pair of sockets when the valve isypushed open by the impact of the piston 24, the plate 41, -or thean-nulus 52 on the -tip of the tappet rod. `Such balls and -springs areshown in dash lines in Figs. IV and V.

LlFig. II yshows the condition ofthe mechanism of the lower cylinderhead 19 just as `the annulus 52 engages the lower spring cushioned tips31 of the tappet rods v44 and 51 near the end of the up stroke of thepiston 2'4. Inthis condition `the inlet valves 43 still are open and theexhaust valves 48 are closed. Continued upward movement of the piston24, piston rod 25 and annulus 52 ythrough a small fraction of an inchwill close the inlet valves 43 and open the exhaust valves 48 so thatthe piston again can descend.

The piston rod 25 terminates in a replaceable bit 55 which as the pistonreciprocates chisels the rocky away with rapidly repeated blows. Thepiston and piston Arod are free to rotate about their axis so the bit'bores a hole that is approximately round and as the entire machinedances about, ythe hole is larger in diameter than the width of the bit.The exhaust blast is directed vby the exhaust pipe 35 through a port 56in the ring 10 into the .hole .around .the bit 55 to sweep away .thedebris and carry it up along the outside of the shell 8.

Friction reducing bushings of oil impregnated metal, piston rings,gaskets and suitable packing to minimize leakage are employed in themachine wherever their employment is advantageous. By unscrewing thering 10 the engine can be withdrawn from the shell for cleaning, repairor adjustment.

Following are approximate statistics of a typical machine:

yOuter shell .8: outside diameter 41/2 inches; length 7 feet. Cylinder12: inside diameter 3 inches; length 61/2 inches. Piston stroke: 41/2inches.

Expansive fluid pressure: 200 pounds per square inch. Total pressure oncylinder: 1400 pounds.

Strokes per minute: 1200 to 1400.

Dimensions, pressures etc. can be varied as desired.

When the machine is in action the bit attacks the rock with high kineticenergy. The Hforce of the rapidly repeated Oppositely directed reactionsor kicks against the cylinder heads is so great that the eiect ofgravity on the lmass o f the machine is comparatively negligible. Theintervals between oppositely directed kicks are so short the inertia oflthe machine is s o great that the machine hovers practially motionlessat about the level at which it would stand on the bit 55 if the piston24 were stopped at the bottom of its stroke. As the drilling progressesthe machine gradually descends. When the hole to be drilled -is so deepthat the entire shell 8 may descend into it, a cable or rope is attachedto the shell for .use when the machine is to be pulled out `of lthehole.

It is to be understood that the foregoing description and theaccompanying drawings are yexemplary only and that the invention issusceptible to variation and modification within the spirit and scope ofthe subjoined claims.

Having described the invention, I claim:

l. In a drilling machine, in combination, an outer tubular shell, acomposite engine casing removably mounted within said outer tubularshell, said composite yengine casing comprising a tubular chest, atubular cylinder and a tubular bearing supporting section, there being,an upper cylinder head interposed between said chest and said`-cylinder and Va lower cylinder head interposed between said cylinderand said tubular bearing supporting section, a bearing supported inspaced relation to said lower cylinder head by said tubular bearingsupporting section, a reciprocatory piston within said cylinder, apiston rod fixed to said piston and slidable through said lower cylinderhead and said bearing, an annulus Vxed to said piston rod and locatedwithin said tubular bearing Vsupporting section, a chisel like bitsecured to the lower extremity of said piston rod, an auxiliary -rod4iixed to said piston .and slidable through said upper cylinder head, aplate tixed to said auxiliary rod and located within said chest, meansfor continuously supplying 4,expansive fluid to said chest, a conduitfor conducting such iluid to said upper cylinder head and said -lower`cylinder head, there being an inlet passage in said ,upper cylinderhead leading from said conduit .to space `in said cylinder above saidpiston, an inlet valve for closing `and opening said inlet passage, aninlet ltappet rod rigidly connected with said inlet valve and having itslower end extending into said cylinder and its upper end extending intosaid chest, said inlet tappet .rod having spring cushioned vupper landlower tips the lower tip being so located as to be engaged by saidreciprocatory ypiston .fas said piston nears the upper limit of itsreciprocatory movement whereby said inlet tappet rod is -pushed up toopen said inlet valve, the upper tip being so located as to vbe lengagedby said plate as said reciprocatory vpiston nears the lower limit of itsreciprocator'y movement whereby said inlet tappet rod is pushed down toclose said inlet valve, anexhaust channel extending from said uppercylinder head and said lower cylinder head to discharge exhaust iluidadjacent said bit, there being an exhaust passage in said upper cylinderhead leading from the space in said cylinder above said piston to saidexhaust channel, an exhaust valve for closing and opening said exhaustpassage, an exhaust tappet rod rigidly connected with said exhaust Valveand having its lower end extending into said cylinder and its upper endextending into said chest, said exhaust tappet rod having springcushioned tips, the lower tip being so located as to be engaged by saidreciprocatory piston as said reciprocatory piston nears the upper limitof its reciprocatory movement whereby said exhaust tappet rod is pushedup to close said exhaust valve, the upper tip being so located as t0 beengaged by said plate as said reciprocatory piston nears the lower limitof its reciprocatory movement whereby said exhaust tappet rod is pusheddown to open said exhaust valve, said lower piston head having inlet andexhaust passages, inlet and exhaust valves and inlet and exhaust tappetrods corresponding in relationship to each other and in function to thesimilarly denominated elements in said upper cylinder head, the tappetrods of said lower cylinder head being pushed down by said reciprocatorypiston to open the inlet Valve and close the exhaust valve in said lowercylinder head when said reciprocatory piston nears the lower limit ofits reciprocatory movement and being pushed up by said annulus xed tosaid piston rod to close the inlet valve and open the exhaust vaive insaid lower cylinder head when said reciprocatory piston nears the upperlimit of its reciprocatory movement, whereby said bit is caused toattack the substance being drilled with a rapid succession of chiselingblows and the machine is caused to hover at such an elevation above thesubstance being so attacked that such blows are delivered with highkinetic energy.

2. In a drilling machine, in combination, an outer tubular shell, acomposite engine casing removably mounted within said outer tubularshell, said composite engine casing comprising a tubular chest, atubular cylinder, an upper cylinder head and a lower cylinder head, abearing supported in spaced relation to said lower cylinder head, areciprocatory piston within said cylinder, a piston rod fixed to saidpiston and slidable through said lower cylinder head and said bearing,an annulus fixed to said piston rod, a chisel like bit secured to thelower extremity of said piston rod, an auxiliary rod iixed to saidpiston and slidable through said upper cylinder head, a plate fixed tosaid auxiliary rod and located within said chest, means for continuouslysupplying expansive fluid to said chest, a conduit for conducting suchfluid to said upper cylinder head and said lower cylinder head, therebeing an inlet passage in said upper cylinder head leading from saidconduit to space in said cylinder above said piston, an inlet valve forclosing and opening said inlet passage, an inlet tappet rod rigidlyconnected with said inlet valve and having its lower end extending intosaid cylinder and its upper end extending into said chest, said inlettappet rod having spring cushioned upper and lower tips the lower tipbeing so located as to be engaged by said reciprocatory piston as saidpiston nears the upper limit of its reciprocatory movement whereby saidinlet tappet rod is pushed up to open said inlet valve, the upper tipbeing so located as to be engaged by said plate as said reciprocatorypiston nears the lower limit of its reciprocatory movement whereby saidinlet tappet rod is pushed down to close said inlet valve, an exhaustchannel extending from said upper cylinder head and said lower cylinderhead., there being an exhaust passage in said upper cylinder headleading from the space in said cylinder above said piston to saidexhaust channel, an exhaust valve for closing and opening said exhaustpassage, an exhaust tappet rod rigidly connected with said exhaust Valveand having its lower end extending into said cylinder and its upper endextending into said chest, said exhaust tappet rod having springcushioned tips, the lower tip being so located as to be engaged by saidreciprocatory piston as said reciprocatory piston nears the upper limitof its reciprocatory movement whereby said exhaust tappet rod is pushedup to close said exhaust valve, the upper tip being so located as to beengaged by said plate as said reciprocatory piston nears the lower limitof its reciprocatory movement whereby said exhaust tappet rod is pusheddown to open said exhaust valve, said lower piston head having inlet andexhaust passages, inlet and exhaust valves and inlet and exhaust tappetrods corresponding in relationship to each other and in function to thesimilarly denominated elements in said upper cylinder head, the tappetrods of said lower cylinder head being pushed down by said reciprocatorypiston to open the inlet valve and close the exhaust valve in said lowercylinder head when said reciprocatory piston nears the lower limit ofits reciprocatory movement and being pushed up by said annulus fixed tosaid piston rod to close the inlet valve and open the exhaust valve insaid lower cylinder head when said reciprocatory piston nears the upperlimit of its reciprocatory movement, whereby said bit is caused toattack the substance being drilled with a rapid succession of chiselingblows and the machine is caused to hover at such an elevation above thesubstance being so attacked that such blows are delivered with highkinetic energy.

3. In a drilling machine, in combination, an outer tubular shell, acomposite engine casing removably mounted within said outer tubularshell, said composite engine casing comprising a tubular chest, atubular cylinder, an upper cylinder head and a lower cylinder head, abearing supported in spaced relation to said lower cylinder head, areciprocatory piston within said cylinder, a piston rod fixed to saidpiston and slidable through said lower cylinder head and said bearing,an annulus ixed to said piston rod, a chisel like bit secured to thelower extremity of said piston rod, an auxiliary rod xed to said pistonand slidable through said upper cylinder head, a plate xed to saidauxiliary rod and located within said chest, means for continuouslysupplying expansive fluid to said chest, a conduit for conducting suchfluid to said upper cylinder head and said lower cylinder head, therebeing an inlet passage in said upper cylinder head leading from saidconduit to space in said cylinder above said piston, an inlet valve forclosing and opening said inlet passage, an inlet tappet rod rigidlyconnected with said inlet valve and having its lower end extending intosaid cylinder and its upper end extending into said chest the lower endbeing so located as to be engaged by said reciprocatory piston as saidpiston nears the upper limit of its reciprocatory movement whereb saidinlet tappet rod is pushed up to open said inlet valve, the upper endbeing so located as to be engaged by said plate as said reciprocatorypiston nears the lower limit of its reciprocatory movement whereby saidinlet tappet rod is pushed down to close said inlet valve, an exhaustchannel extending from said upper cylinder head and said lower cylinderhead, there being an exhaust passage in said upper cylinder head leadingfrom the space in said cylinder above said piston to said exhaustchannel, an exhaust valve for closing and opening said exhaust passage,an exhaust tappet rod rigidly connected with said exhaust valve andhaving its lower end extending into said cylinder and its upper endextending into said chest, the lower end being so located as to beengaged by said reciprocatory piston as said reciprocatory piston nearstherupp'er limit of its reciprocatory movement whereby said exhausttappet rod is pushed up to close said exhaust valve, the upper end beingso located as to be engaged by said plate as said reciprocatory pistonnears the lower limit of its reamat-W9 ciprocatory movement whereby saidexhaust tappet rod is pushed down to open said exhaust valve, said lowerpiston head having inlet and exhaust passages, inlet and exhaust valvesand inlet and exhaust tappet rods corresponding in relationship to eachother and in function to the similarly denominated elements in saidupper cylinder head, the Vtappet rods of said lower cylinder head beingpushed down by said reciprocatory piston to open the inlet valve andclose the exhaust valve in said lower cylinder head when saidreciprocatory piston nears the lower limit of its reciprocatory movementand being pushed up by said annulus xed to said piston rod to close theinlet valve and open the exhaust valve in said lower cylinder head whensaid reciprocatory piston nears the upper limit of its reciprocatorymovement, whereby said bit is caused to attack the substance beingdrilled with a rapid succession of chiseling blows and the machine iscaused to hover at such an elevation above the substance being soattacked that such blows are delivered with high kinetic energy.

4. In a drilling machine, in combination, an outer tubular shell, acomposite engine casing removably mounted within said outer tubularshell, said composite engine casing comprising a tubular chest, atubular .cylinder and a tubular bearing supporting section, there beingan upper cylinder head interposed between said chest and said cylinderand a lower cylinder head interposed between said cylinder and saidtubular bearing supporting section, a bearing supported in spacedrelation to said lower cylinder head by said tubular bearing supportingsection, a reciprocatory piston within said cylinder, a piston rod lixedto said piston and slidable through said lower cylinder head and saidbearing, an annulus fixed to said piston rod and located within saidtubular bearing supporting section, a chisel like bit secured to thelower extremity of said piston rod, an auxiliary rod lixed to saidpiston and slidable through said upper cylinder head, a plate lixed tosaid auxiliary rod and located within said chest, means for continuouslysupplying expansive fluid to said chest, a conduit for conductingsuchfluid to said upper cylinder head and said lower cylinder head,there being an inlet passage in said upper cylinder -head leading fromsaid conduit to space in said cylinder above ysaid piston, an inletvalve for closing and opening said inlet passage, means operative assaid pistou nears the upper limit of its reciprocatory movement to opensaid inlet valve, means operative as said reciprocatory pis-ton nearsthe lower limit of its reciprocatory movement to close said inlet valve,an exhaust channel extending from said upper cylinder head and saidlower cylinder head to ldischarge exhaust fluid adjacent said bit, therebeing an exhaust passage in said upper cylinder head leading from thespace in said cylinder above said piston yto said exhaust channel, anexhaust valve for closing and opening said exhaust passage, meansoperative as said reciprocatory piston nears the upper limit of itsreciprocatory movement to close said exhaust valve, means operative assaid reciprocatory piston nears the lower limit of its reciprocatorymovement to open said exhaust valve, said lower piston head having inletand exhaust passages, and inlet and exhaust valves and valve actuatingmeans all corresponding in relationship to each other and in function tothe similarly denominated elements in said upper cylinder head, wherebysaid bit is caused to attack the substance being drilled with a rapidsuccession of chiseling blows and the machine is caused to hover at suchan elevation above the substance being so attacked that such blows aredelivered with high kinetic energy.

5. In a drilling machine, in combination, an outer tubular shell, acomposite engine casing removably mounted within said outer tubularshell, said composite engine casing comprising a tubular chest, atubular cylinder, an upper cylinder head and a lower cylinder head, abearing supported in spaced relation to said Vlower cylinder head, alreciprocatory piston within said cylinder, a piston rod lixed to saidpiston and Vslidable through said lower cylinder head and said bearing,an annulus lixed to said piston rod, a chisel like bit secured to thelower extremity of said piston rod, an auxiliary rod xed to said pistonand slidable through said upper cylinder head, a plate fixed to saidauxiliary rod and located within said chest, means for continuouslysupplying expansive uid to said chest, a conduit for conducting suchliuid to said upper cylinder head and said lower cylinder head, therebeing an inlet passage in said upper cylinder head leading from saidconduit to space in said cylinder 'above said piston, an inlet valve forclosing and opening said inlet passage, means operative as said pistonnears the upper limit of its reciprocatory movement to open said inletvalve, means operative as said reciprocatory piston nears the lowerlimit of its reciprocatory movement to close said inlet valve, anexhaust channel extending from said upper cylinder head and said lowercylinder head, there being an exhaust passage in said upper cylinderhead leading from the space in said cylinder above said piston to saidexhaust channel, an exhaust valve for closing and opening said exhaustpassage, means operative as said reciprocatory piston nears the upperlimit of its reciprocatory movement to close said exhaust valve, meansoperative as said reciprocatory piston nears the lower limit of itsreciprocatory movement to open said exhaust valve, said lower pistonhead having inlet and exhaust passages, and inlet and exhaust valves andvalve actuating means all corresponding in relationship to each otherand in function to the similarly denominated elements in said uppercylinder head, whereby said bit is caused to attack the substance beingdrilled with a rapid succession of chiseling blows and the machine iscaused to hover at such an elevation above the substance being soattacked that such blows are delivered with high kinetic energy.

6. A drilling machine comprising, in combination, a tubular chest, atubular cylinder and a tubular bearing supporting section, there beingan upper cylinder head interposed between said chest and said cylinderand a lower cylinder head interposed between said cylinder and saidtubular bearing supporting section, a bearing supported in spacedrelation to said lower cylinder head by said tubular bearing supportingsection, a reciprocatory piston within said cylinder, a piston rod iixedto said piston and slidable through said lower cylinder head and saidbea-ring, an annulus xed to said piston rod and located within saidtubular bearing supporting section, a chisel like bit secured to thelower extremity of said piston rod, an auxiliary rod fixed to saidpiston and slidable through said upper cylinder head, a plate iixed tosaid auxiliary rod and located within said chest, means for continuouslysupplying expansive fluid to said chest, a Aconduit for conducting suchuid to said upper cylinder head and said lower cylinder head, therebeing an inlet passage in said upper cylinder head leading from saidconduit to space in said cylinder above said piston, an inlet valve forclosing and Opening said inlet passage, an inlet tappet rod rigidlyconnected with said inlet valve and having its lower end extending intosaid cylinder and its upper end extending into said chest, said inlettappet rod having spring cushioned upper and lower tips theV lower tipbeing so located as to be engaged by said reciprocatory piston as saidpiston nears the upper limit of its reciprocatory movement whereby saidinlet tappet rod is pushed up to open said inlet valve, the uppertipbeing so located as to be engaged by said plate as said reciprocatorypiston nears the lower limit of its reciprocatory movement whereby saidinlet tappet rod is pushed down to close said inlet valve, an exhaustchannel extending from said upper cylinder head and said lower cylinderhead to discharge exhaust iluid adjacent said bit, there being anexhaust passage in said upper cylinder head leading from the space insaid cylinder above said piston to said exhaust channel, an exhaustvalve vfor closing and opening said exhaust passage, an exhaust tappetrod rigidly connected with said exhaust valve and having its lower endextending into said cylinder and its upper end extending into saidchest, said exhaust tappet rod having spring cushioned tips, the lowertip being so located as to be engaged by said reciprocatory piston assaid reciprocatory piston nears the upper limit of its reciprocatorymovement whereby said exhaust tappet rod is pushed up to close saidexhaust valve, the upper tip being so located as to be engaged by saidplate as said reciprocatory piston nears the lower limit of itsreciprocatory movement whereby said exhaust tappet rod is pushed down toopen said exhaust valve, said lower piston head having inlet and exhaustpassages, inlet and exhaust valves and inlet and exhaust tappet rodscorresponding in relationship to each other and in function to thesimilarly denominated elements in said upper cylinder head, the tappetrods of said lower cylinder head being pushed down by said reciprocatorypiston to open the inlet valve and close the exhaust valve in said lowercylinder head when said reciprocatory piston nears the lower limit ofits reciprocatory movement and being pushed up by said annulus fixed tosaid piston rod to close the inlet valve and open the exhaust valve insaid lower cylinder head when said reciprocatory piston nears the upperlimit of its reciprocatory movement, whereby said bit is caused toattack the substance being drilled with a rapid succession of chiselingblows and the machine is caused to hover at such an elevation above thesubstance being so attacked that such blows are delivered with highkinetic energy.

7. A drilling machine comprising, in combination, a tubular chest, atubular cylinder, an upper cylinder head and a lower cylinder head, abearing supported in spaced relation to said lower cylinder head, areciprocatory piston within said cylinder, a piston rod fixed to saidpiston and slidable through said lower cylinder head and said bearing,an annulus xed to said piston rod, a chisel like bit secured to thelower extremity of said piston rod, an auxiliary rod xed to said pistonand slidable through said upper cylinder head, a plate fixed to saidauxiliary rod and located within said chest, means for continuouslysupplying expansive fluid to said chest, a conduit for conducting suchuid to said upper cylinder head and said lower cylinder head, therebeing an inlet passage in said upper cylinder head leading from saidconduit to space in said cylinder above said piston, an inlet valve forclosing and opening said inlet passage, an inlet tappet rod rigidlyconnected with said inlet valve and having its lower end extending intosaid cylinder and its upper end extending into said chest, said inlettappet rod having spring cushioned upper and lower tips the lower tipbeing so located as to be engaged by said reciprocatory piston as saidpiston nears the upper limit of its reciprocatory movement whereby saidinlet tappet rod is pushed up to open said inlet valve, the upper tipbeing so located as to be engaged by said plate as said reciprocatorypiston nears the lower limit of its reciprocatory movement whereby saidinlet tappet rod is pushed down to close said inlet valve, an exhaustchannel extending from said upper cylinder head and said lower cylinderhead there being an exhaust passage in said upper cylinder head leadingfrom the space in said cylinder above said piston to said exhaustchannel, an exhaust valve for closing and opening said exhaust passage,an exhaust tappet rod rigidly connected with said exhaust valve andhaving its lower end extending into said cylinder and its upper endextending into said chest, said exhaust tappet rod having springcushioned tips, the lower tip being so located as to be engaged by saidreciprocatory piston as said reciprocatory piston nears the upper limitof its reciprocatory movement whereby said exhaust tappet rod is pushedup to close said exhaust valve, the upper tip being so located as to beengaged by said plate as said reciprocatory piston nears the lower limitof its reciprocatory movement whereby said exhaust tappet rod is pusheddown to open said exhaust valve, said lower piston head having inlet andexhaust passages, inlet and exhaust valves and inlet andexhaust tappetrods corresponding in relationship to each other and in function to thesimilarly denominated elements in said upper cylinder head, the tappetrods of said lower cylinder head being pushed down by said reciprocatorypiston to open the inlet valve and close the exhaust valve in said lowercylinder head when said reciprocatory piston nears the lower limit ofits reciprocatory movement and being pushed up by said annulus xed tosaid piston rod to close the inlet valve and open the exhaust valve insaid lower cylinder head when said reciprocatory piston nears the upperlimit of its reciprocatory movement, whereby said bit is caused toattack the substance being drilled with a rapid succession of chiselingblows and the machine is caused to hover at such an elevation above thesubstance being so attacked that such blows are delivered with highkinetic energy.

8. A drilling machine comprising, in combination, a tubular chest, atubular cylinder, an upper cylinder head and a lower cylinder head, abearing supported in spaced relation to said lower cylinder head, areciprocatory piston within said cylinder, a piston rod fixed to saidpiston and slidable through said lower cylinder head and said bearing,an annulus fixed to said piston rod, a chisel like bit secured to thelower extremity of said piston rod, an auxiliary rod xed to said pistonand slidable through said upper cylinder head, a plate xed to saidauxiliary rod and located within said chest, means for continuouslysupplying expansive fluid to said chest, a conduit for conducting suchuid to said upper cylinder head and said lower cylinder head, therebeing an inlet passage in said upper cylinder head leading from saidconduit to space in said cylinder above said piston, an inlet valve forclosing and opening said inlet passage, an inlet tappet rod rigidlyconnected with said inlet valve and having its lower end extending intosaid cylinder and its upper end extending into said chest, the lower endbeing so located as to be engaged by said reciprocatory piston as saidpiston nears the upper limit of its reciprocatory movement whereby saidinlet tappet rod is pushed up to open said inlet valve, the upper endbeing so located as to be engaged by said plate as said reciprocatorypiston nears the lower limit of its reciprocatory movement whereby saidinlet tappet rod is pushed down to close said inlet valve, an exhaustchannel extending from said upper cylinder head and said lower cylinderhead, there being an exhaust passage in said upper cylinder head leadingfrom the space in said cylinder above said piston to said exhaustchannel, an exhaust valve for closing and opening said exhaust passage,an exhaust tappet rod rigidly connected with said exhaust valve andhaving its lower end extending into said cylinder and its upper endextending into said chest, the lower end being so located as to beengaged by said reciprocatory piston as said reciprocatory piston nearsthe upper limit of its reciprocatory movement whereby said exhausttappet rod is pushed up to close said exhaust Valve, the upper end beingso located as to be engaged by said plate as said reciprocatory pistonnears the lower limit of its reciprocatory movement whereby said exhausttappet rod is pushed down to open said exhaust valve, said lower pistonhead having inlet and exhaust passages, inlet and exhaust valves andinlet and exhaust tappet rods corresponding in relationship to eachother and in function to the similarly denominated elements in saidupper cylinder head, the tappet rods of said lower cylinder head beingpushed down by said reciprocatory piston to open the inlet valve andclose the exhaust valve in said lower cylinder head when saidreciprocatory piston nears the lower limit of its reciprocatory movementand being pushed up by said annulus fixed to said piston rod to closethe inlet valve and open the exhaust valve in said lower cylinder headwhen said reciprocatory piston nears the upper limit of itsreciprocatory movement, whereby said bit is caused to attac-k thesubstance being drilled with a rapid succession of chiseling blows andthe -machine is caused to hover at such an elevation above the substancebeing so attacked that such blows are delivered w-ith high kineticenergy.

9. A drilling machine comprising, -in combination, a tubular chest, atubular cylinder and a tubular bearing supporting section, there beingan upper cylinder head interposed between sa-id chest and said cylinderand a lower cylinder head -interposed between said cylinder and saidtubular bearing supporting section, -a bearing supported in spacedrelation to said lower cylinder head by said tubular bearing support-ingsection, -a reciprocatory piston within said cylinder, a piston rodlixed to sa-id piston and slidable through said lower cylinder head andsaid bearing, an annulus Ifixedl to said piston rod and located withinsaid tubular 'bearing support-ing section, a chisel like bit secured vtothe lower extremity of ysaid piston rod, an auxiliary rod iixed to saidpiston and slidable through said upper cylinder-head, a plate -xed tosaid auxiliary rod and located within sa-id chest, means torcontinuously suppl-ying expansive fluid `to said chest, a conduit forconduct-ing such fluidl to said upper cylinder head and said lowercylinder head, there being an inlet passage in said upper cylinder headleading yfrom said conduit 'to space in -said cylinder above saidpiston, -a-n inlet vvalve for closing and opening said inlet passage,means operative as said piston nears the upper limit of itsreciprocatory movement to open said inlet -v-alve, means operative assaid reciprocatory piston nears the lower limit of its reciprocatorymovement to close said inlet valve, an exhaust channel extending fromsaid upper cylinder head and said lower cylinder head to dischargeexhaust fluid adjacent said bit, there lbein-g an exhaust passage insaid upper cylinder head leading from the space in said cylinder abovesaid piston -to said exhaust channel, an exhaust valve for closing andopening said exhaust passage, means operative as sa-id reciprocatorypiston nears the upper limit of its reciprocatory movement to close saidexhaust valve, means operative as `said reciprocatory piston nears thelower lim-it of its reciprocatory movement to open said exhaust valve,said lower piston head having inlet and exhaust passages, and inlet andexhaust valves and valve actuating means all corresponding inrelationship to each other and nin function to the similarly denominatedelements `in `said upper cylinder head, whereby said bit is caused toattack the substance being drilled with a rapid succession ,of chiselingblows and the machine is caused to hover ,at such an elevation above thesubstance being so -attacked that such blows are delivered 4with lhighkinetic energy.

l0. A drilling machine comprising, in combination, a tubular chest, atubular cylinder, an upper cylinder head and a lower cylinder head, abearing supported in spaced relation to said lower cylinder head, areciprocatory piston within said cylinder, a piston rod xed to saidpiston and Aslidable through said lower cylinder head and said bearing,an annulus ixed to said piston rod, a chisel like bit secured to thelower extremity of said piston rod, an auxiliar-y rod fixed to saidpiston and slidable through said upper cylinder head, a plate fixed tosaid auxiliary rod and located within said chest, means for continuouslysupplying expansive fluid to said chest, a conduit for conducting suchuid to said upper cylinder head and said lower cylinder head, therebeing an inlet passage in said upper cylinder head leading from saidconduit to space in -said cylinder above said piston, an inlet valve forclosing and opening said inlet passage, means operative as said pis-ton-nears the upper limit of its reciprocatory movement to open said inletvalve, means operative as said reciprocatory piston nears the lowerlimit of its reciprocatory movement to close said inlet valve, anexhaust channel lextending from said upper cylinder head and said lowercylinder head, there being an exhaust passage in said upper cylinderhead leading from the space in said cylinder above -said piston to saidexhaust channel, an exhaust valve lfor closing and opening said exhaustpassage, means operative as said reciprocatory piston nears the upperlimit of its reciprocatory movement to close said exhaust valve, meansoperative as said reciprocatory piston nears the lower limit of itsreciprocatory movement to open said exhaust valve, said lower pistonhead having inlet and exhaust passages, and inlet and exhaust v-alvesand valve actuating means all corresponding in relationship to eachother and in function to the similarly denominated elements in saidupper cylinder head, whereby said bit is caused to attack the substancebeing drilled with a rapid succession of chiseling blows and the machineis caused to hover at such an elevation above the substance -being soattacked that such blows are delivered with high kinetic energy.

References Cited in the tile of this patent 'UNITED STATES PATENTS`860,660 Heldmaier July 23, 1907 96,8016 Williome Aug. 23, 19101,569,183 Herman et al. Ian. l2, 1926

